/*
Given a sorted linked list, delete all duplicates such that each element appear only once.

For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.
*/


/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *deleteDuplicates(ListNode *head) {
        ListNode *cur = head;
        while (cur && cur->next) {
            ListNode *next = cur->next;
            if (cur->val == next->val) {
                cur->next = next->next;
                delete next;
            } else cur = next;
        }
        return head;
    }
};

#if 0
class Solution {
public:
    ListNode *deleteDuplicates(ListNode *head) {
        if (!head) return head;
        ListNode *start=head, *cur=head;
        while (cur) {
            if (cur->val == start->val) {
                start->next = cur->next;
                if (cur != start) delete cur; 
                cur = start->next;
            } else {start = cur;} // detect new block
        }
        return head;
    }
};
#endif
